The study characterizes the clinical presentation of ischemic colitis (IC) associated with myocardial infarction (MI) and helps determine whether the primary mechanism for this association is thrombus, embolus, or localized nonocclusive mesenteric ischemia (NOMI) associated with systemic hypotension.

We compared 23 study patients presenting with IC occurring simultaneously with or within 3 days after MI who were admitted to 5 medical centers versus (1) 32 patients with IC without MI (IC-controls) or (2) 32 patients with MI without IC (MI-controls).

Of 17,500 patients admitted to the study sites with MI, 23 (0.13%) had IC. Study patients had a high in-hospital mortality of 39%. An Acute Physiology and Chronic Health Evaluation (APACHE) II score greater than 15 was a significant predictor of mortality in these patients (P<.04). Compared with the IC-controls, study patients had a significantly lower mean arterial pressure (MAP) (76.0 ± 17.1 mm Hg vs 98.3 ± 18.6 mm Hg, P<.0001) and a significantly higher rate of hypotension (57% vs 9%, odds ratio [OR] = 12.6, confidence interval [CI]: 3.10-49.7, P<.001). The 2 groups, however, had a similar mean number of risk factors for thromboembolism per patient. Study patients had more severe illness than IC-controls, as demonstrated by mean APACHE II scores (19.0 ± 5.5 vs 10.4 ± 4.8, P<.0001). Study patients had a significantly higher incidence of complications, including respiratory failure (57% vs 13%, P=.001), altered mental status (48% vs 13%, P<.01), and renal insufficiency or failure (61% vs 28%, P<.04). Study patients had a significantly lower minimum hematocrit. Study patients had a significantly higher rate of prolonged hospitalization (>30 days) or in-hospital death (74% vs 19%, OR = 12.3, CI: 3.47-43.5, P<.0001). Compared with MI-control patients, study patients had a significantly lower MAP, significantly higher rate of hypotension, much higher mean APACHE II score, much higher incidence of complications, and significantly worse hospital outcome.

Patients with both IC and MI present as a clinically distinct group from patients with either IC alone or MI alone. They have significantly more complications and worse in-hospital prognoses. They present with a dramatically lower MAP and a higher frequency of hypotension. This last finding suggests that the most common and most important mechanism for IC with MI may be hypotension from cardiogenic shock. Hypotension is the cardinal risk factor for generalized NOMI with acute mesenteric ischemia and may be an important risk factor for localized NOMI with IC. An APACHE II score greater than 15 may be a predictor of mortality from IC after MI.